1. Field of the Invention
The present invention relates to a tape cassette for use in, an image or an audio recording and reproducing apparatus such as a video tape recorder or an external memory apparatus for various data processing devices.
2. Description of the Related Art
Recently in the field of video tape recorders, especially of the ones integrated with a camera, active studies have been made for reducing the size, weight and thickness. An important point in reducing the size and thickness lies in how to reduce the total height of a tape cassette in a state of being mounted in a video tape recorder. When a tape cassette is mounted in a video tape recorder, a front cover of the tape cassette is pivoted to above the tape cassette so as to expose a tape. In order to minimize the height of the tape cassette in this state, various proposals have been made for a mechanism for opening and closing the front cover. Such proposals are described in, for example, Japanese Patent Publication Nos. 63-16824 and 63-16825.
A tape cassette disclosed in Japanese Patent Publication No. 63-16824 will be described with reference to the figures.
FIG. 30 is a perspective view of a conventional tape cassette 19 in a state where a front cover is closed. FIG. 31 is a perspective view of the tape cassette 19 An a state where the front cover As opened. FIG. 32 is a perspective view of a housing 1 of the tape cassette 19 with covers thereof being omitted. FIG. 33 is a cross sectional view of the housing 1 with the covers thereof being omitted. FIG. 34 is a perspective view of a front cover 9 and a top cover 11. FIGS. 35 through 37 are views illustrating an operation for opening the front cover.
As is shown in FIGS. 30 through 37, the tape cassette 19 includes the housing 1, which includes a top half 2 and a bottom half 3. The housing 1 accommodates ,pdates a pair of rotatable tape reels 63 (FIG. 33). A tape 7 is wound around the tape reels 63 and further stretched between a pair of tape guides 8 (FIG. 31) provided on a face of the housing 1. A direction An which the tape 7 is stretched between the tape guides 8 will be referred to as the "tape stretching direction". The housing 1 has a front opening 4 along substantially the total width of the tape cassette 19 at a face where the tape is stretched, a bottom opening 8 and a top opening 6. The bottom opening 5 and the top opening 6 adjoin the front opening 4.
The front opening 4 is covered with a front cover 9 (FIG. 34) including a flat rectangular front portion 9a and a pair of side portions 9b and 9c (FIGS. 30 and 31) extended perpendicular to two side ends in the tape stretching direction of the front portion 9a. The front cover 9 is supported by the housing 1 so as to be pivotal about support pans 10 (only one is shown) each provided on an inner face of the side portion 9b, 9c.
As is shown in FIG. 34, the front cover 9 has a torsion bar 58 formed of a synthetic resin extended in the tape stretching direction along a top end portion 57 thereof. Ends 59 (only one is shown) of the torsion bar 58 are rotatably supported by end portions 60 (only one is shown) of the top end portion 57. A central portion 61 of the torsion bar 58 is fixed to the top end portion 57. In the vicinity of the ends 59 of the torsion bar 58, a top cover 11 is attached to the torsion bar 58 through ends 62 (only one is shown) of the top cover 11. The top cover 11, which covers the top opening 6, slides on the top half 2 in association with the opening operation of the front cover 9 as is shown in FIGS. 35 through 37. In such a construction, when the front cover 9 is pivoted to above the top half 2, the torsion bar 58 is twisted, thereby loading the top cover 11 counterclockwise in FIGS. 35 through 37.
As is shown in FIGS. 35 through 37, the tape 7 is accommodated in a space defined by the front cover 9, an inner plate 12 opposed to a substantially upper half portion of the front cover 9, and a rear cover 13. The rear cover 13 and the top cover 11 are connected to each other so as to be pivotal about support pins 14 and 15 with respect to the front cover 9. The rear cover 13 has projections 16 on a rear face thereof, and the projections 16 each has a guide pin 18 at a tip thereof. Each guide pin 18 is engaged with a guide groove 17 (only one is shown in FIG. 31) provided on an inner face of each tape guide 8 so as to slide along the guide groove 17.
In association with the opening and closing operation of the front cover 9, the top cover 11 and the rear cover 13 are also opened and closed. A locus of the rear cover 13 is always restricted by the sliding movement of the guide pins 18 along the guide grooves 17. In contrast, the top cover 11, which is connected to the front cover 9 through the torsion bar 58, is loaded counterclockwise as mentioned above when The front cover 9 is closed, opened and in the middle of the pivoting operation as is shown in FIGS. 35 through 37. If an external force is applied to the top cover 11 so as to move the top cover 11, the top cover 11 is easily opened or closed. Accordingly, when the tape cassette 19 is mounted in or dismounted from a recording and reproducing apparatus, the top cover 11 is hooked by the apparatus, and thus hampers a smooth mounting or dismounting operation.
As is apparent from FIG. 37, when the front cover 9 is opened, there is made a large recess 64 at bottom of the tape cassette 19. This causes problems in that the tape cassette 19 is hooked by the apparatus and that dust or other foreign objects are allowed to enter the recess 64.
In a case where a small tape cassette which is smaller than a cassette having a size conforming to the apparatus is used, the small tape cassette is accommodated in an adapter before being mounted in the apparatus. FIG. 38 shows the tape cassette 19 accommodated in an adapter 66 as the small tape cassette. A top face of the tape cassette 19 which is exposed does not constitute a flat face with a top face of the adapter 66, there is made a recess 67 at the top face. When the tape cassette 19 is mounted in the apparatus in such a state, a perimeter of the recess 67 is hooked by the apparatus, causing problems that dust or other foreign objects are allowed easy access into the tape cassette 19, smooth mounting and dismounting is hampered, and thus the tape cassette 19 is easily damaged during the mounting and dismounting operation.